The project consists of nonclinical absorption, distribution, metabolism, elimination (ADME) studies to support NIDA's medications development program. The nonclinical ADME studies for this contract typically include in vitro and in vivo metabolism studies, and toxicokinetics of new medications. In addition, this contract also involves analytical services which include structure identification of major metabolites by mass spectrometry or nuclear magnetic resonance (NMR), and the development of sensitive and specific assays for a drug and its metabolites in biological matrices using methods such as high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), liquid chromatography with tandem mass spectrometry (LC/MS/MS/, gas chromatography-mass spectrometry (GC-MS).